In power stages, a switch controlled by a control signal is typically implemented by a metal-oxide-semiconductor transistor, commonly referred to using the acronym “MOS”. A MOS transistor is driven by a control voltage. FIG. 1 shows a section of a power stage of a switched-mode power supply comprising a switch 10 controlled by control voltage VG. The controlled switch 10 is a MOS transistor comprising a gate coupled to a node G, a drain coupled to a node D which is brought to a potential VBAT, and a source coupled to a node S which is brought to a potential VNEG. The control voltage VG is applied to the node G. Depending on the value of the control voltage VG, the voltage VDS between the source and the drain of the transistor is either substantially zero (conducting transistor, corresponding to the closed state of the switch), or substantially equal to the voltage corresponding to the difference between the potential VBAT and the potential VNEG (non-conducting transistor, corresponding to the open state of the switch).
In the case of a power stage configured to provide a positive potential VPOS of about 1.8 V and the negative potential VNEG of about −1.8 V, from the potential VBAT of 4.8 V supplied by a battery, the voltage VDS may reach 6.6 V. However, the MOS transistors able to support such a high voltage VDS are costly and/or unsuitable for production and application via reliable and cost-efficient industrial processes, particularly for the mass production of electrical circuits such as those used in the manufacture of mobile telephones.